Five slippery cars enter a wind tunnel; one slinks out a winner.

Like a thief in the night, wind resistance is a stealthy intruder that saps your speed and murders your mileage without leaving fingerprints. The gentle murmur of air streaming over, under, and through your car belies the wind’s heinous ways.

Even if there’s no alternative to driving through Earth’s atmosphere, we can at least fight wind resistance with science. Aerodynamics—the study of air in motion—can lift our top speeds, curb our fuel consumption, and, if we’re smart about it, keep our tires stuck to the pavement.

Long before automotive engineers fretted over aerodynamics, ­aviation pioneers defined the basic principles of drag and lift. Inspired by birds and airships, early speed demons also toyed with streamlined shapes. The first car to crack 60 mph (in 1899) was an electrically propelled torpedo on wheels called, hilariously, “La Jamais Contente” (“The Never Satisfied”). Grand Prix racers took up the cause in the early 1920s; the following decade, Auto Union and Mercedes-Benz raced toward 300 mph with streamliners developed in German wind tunnels. Half a century after Chuck Yeager broke the sound barrier in flight, Andy Green drove his ThrustSSC a satisfying 763 mph across Nevada’s Black Rock desert.

Now it’s our turn. Car and Driver gathered five slippery cars to study their drag and lift properties at a wind tunnel whose name and location we swore not to reveal. We had two goals in mind: first, to learn the fine points of blowing air over automobiles in a test chamber; second, to determine which brand did the best job optimizing its car’s aero performance.

There are reasons why you haven’t read this story before. Every major carmaker owns and operates a wind tunnel, but those facilities are busy around the clock, as engineers work to stay ahead of the rapidly ­rising EPA-mileage tide. Inter-company rivalries are another issue foiling easy access. While manufacturers often tout the slipperiness of their products, comparisons with competitive models are rare.

The expert in charge at our clandestine test location explains: “All wind tunnels strive to accurately quantify the aerodynamics a car will experience in the real world. The vehicle and the tunnel constitute a system with complex interactions. As a result, drag and lift measurements on a particular vehicle can vary from one tunnel to another.”

A group of vehicles may rank differently in different tunnels, he says. This is why most manufacturers have so little faith in aero numbers measured outside their own facilities. Coast-down testing, which logs the car’s speed as it decelerates, is often touted as the better “real-world” measure of a car’s aerodynamic properties. “That may be true in principle, but accurate results are difficult to achieve in practice because variations in wind, driveline temperatures, and tire qualities influence the results. The beauty of wind tunnels is their tight control over variables.”

Our winner here will be the car with the lowest drag area, which is the product of the shape’s frontal area and its drag ­coefficient and the true measure of a car’s wind-cheating ability [see “A Somewhat Long-Winded Glossary” below]. With that, we humbly present our first ever aero comparo.

A SOMEWHAT LONG-WINDED GLOSSARY

Aerodynamic Horsepower: The power required to drive a vehicle through the atmosphere (not including driveline and tire-rolling losses). It increases with the cube of velocity, so aero power at 100 mph is 2.9 times the power requirement at 70 mph.

Drag Area: The product of the drag coefficient and frontal area is the best measure of any car’s aero performance because it’s directly proportional to the horizontal force measured in a wind tunnel and experienced on the road.

Drag Coefficient (CD): A dimensionless parameter used to quantify aerodynamic efficiency in the horizontal (drag) plane.

Frontal Area: The largest horizontal view of a car. We used a 200-mm camera lens positioned 150 feet from the vehicle to take a digital photo, which we analyzed using Siemens Solid Edge CAD software.

Lift: Air flowing over and under the car and through the grille can diminish wheel loading and, in extreme cases, deteriorate handling. Air dams and spoilers are effective countermeasures.

Wind Resistance (Drag): A force proportional to the drag area, it increases with the square of the vehicle speed.

Streamlines: Wind-tunnel operators add small quantities of smoke to the airflow to reveal how the wind moves around, under, or through the test vehicle.